Processes for the production of acrylic acid by vapor phase catalytic oxidation of acrolein and acrolein precursors, such as allyl alcohol and propylene, are well known in the prior art. For example processes for such are disclosed in U.S. Pat. No. 3,065,264, issued Nov. 20, 1962 to Theadore A. Koch et al and in U.S. Pat. No. 3,405,172, issued Oct. 8, 1968 to Christopher J. Brown, et al. Such processes involve passing acrolein or an acrolein precursor, that is a compound which gives rise to acrolein under the reaction conditions, over an oxidation catalyst at an elevated temperature, water being present in the feed in some instances. High conversions to acrylic acid are obtained, however, the reactor effluent will contain some acrolein which (along with other compounds) needs to be separated from the acrylic acid monomer. It is desirable to both rapidly cool the reaction product and to rapidly remove any acrolein present. The rapid cooling seems to prevent polymer formation while the rapid removal of acrolein is critical in eliminating acrolein contamination in the downstream acrylic acid recovery system. A rapid quench such as that disclosed in U.S. Pat. No. 3,405,172, referred to above, has been used to accomplish such. These rapid quench systems operate so as to immediately condense essentially all of the condensibles in the reactor effluent, but have been found to be undesirable in that in such systems the acrolein unduly reacts with the water present to form hydroxypropionaldehyde or reacts with itself to form oligomers. These products will later decompose back to form acrolein downstream in the distillation towers of an acrylic acid recovery system and contaminate the acrylic acid product.